Method and apparatus for making electric conductor cord



June 18, 1940. H, H, wERMlNE 2,204,782

METHOD AND APPARATUS FOR MAKING ELECTRIC CONDUCTOR CORD Filed April 15, 1936 24 'I/ 16 z l 20 J0 12o ti S;

Patented June 18, 1940 UNITED STATES PATENT OFFICE ME TH OD AND APPARATUS FOR MAKING Belden Manufacturing Company,

Chicago, 111.,

a corporation of Illinois Application April 13, 1936, Serial No. 74,053

13 Claims.

This invention relates to improvements in electrical conductors and more particularly to improvements in duplex or plural wire conductors, the use of which frequently requires separation of the respective wires from each other while retaining thereon adequate insulation coverings. 'This invention is furthermore particularly related to such plural wire conductor cords which conventionally embody a unitary 1m jacket of insulation material, such as rubber,

which, in conventional structures, is difiicult to separate to provide adequate insulation jackets on the conductor wires when separated from each other.

15 The main object of the present invention is to provide an insulation covered electric conductor of the type indicated which may be easily and accurately separated into relatively independent, adequately insulated electric wire porto provide such electric cable or conductor cord which may be made economically and at low cost; and in general, it is the object of the invention to provide improved plural wire electric conductor cord of the character indi-' 3;; cated.

This application is, in part, a continuation of my co-pending application, Serial No. 753,658, filed November 19, 1934.

Other objects and advantages of the invention m will be understood by reference to the following specification and the accompanying drawings (1 sheet), wherein there are illustrated several forms of duplex electric conductor or lamp cord embodying the invention, and preferred methods and apparatus for making such cord.

In the drawing- Fig. 1 is a plan view of a preferred mechanism for producing the improved cord, a portion of the mechanism being illustrated in section.

.m Fig. 2 is a section on the line 2-4 of Fig. 1.

Fig. 3 is a section on the line 3-3 of Fig. 1.

Fig. 4 is a section on the line 4-4 of Fig. 1.

Fig. 5 is a section corresponding to a portion of Fig. 1, but showing a modified arrangement which eliminates the requirement of certain parts of the mechanism shown in Fig. 1, and

Fig. 6 is a section on the line 6-6 of Fig. 5.

Figs. 7, 8, 9, 10 and 11 are sections corresponding to Fig. 4, but respectively showing modified in forms of conductor which may be produced in accordance with the invention.

Referring now to Figs. 1 to 4 inclusive, the form of duplex conductor there illustrated embodies a pair of electric wires l and II which are embedded in rubber jackets or coverings I2 and I3 respectively. The rubber jackets l2 and I3 are adhesively united along a joint designated l4 lying in a plane extending longitudinally of the conductor cord between the wires l0 and H to permit convenient separation of said jackets, 5 as by tearing them apart along the joint, as will hereinafter more fully appear. In this instance, the joint |4 between the two conductor cord portions |2 and I3 is made in two parts designated M and l which are disposed respectively on opposite sides of a central opening or passageway I5.

The production of a duplex conductor embodying the structure just described is effected by means of an extruding head designated I6, the same being of the general type of extruding head which is commonly employed in the insulated wire production art. It embodies a hollow head into which plastic rubber, rubber composition or other suitable insulating material 20 designated I1 is fed by suitable means (not shown), and a wire-guiding device designated H! which guides the conductor wires l0 and II into, and through the extruding head and through suitable openings in a die l9 which is carried by a removable element 20. The member 20 may, for example, be screw-tlneaded into a suitably tapped opening in the extruding head so that the member may be removed to permit renewal or replacement of the die element I9 when de sired, and also to permit access to the interior of the extruding head when occasion necessitates.

The wire-guiding mechanism I8 includes a tip 2| which is removably seated in a tubular holder 22, the latter being removably mounted in the extruding head by suitable means, for example, screw-threading as indicated. The tip 2| is provided with a pair of apertures extending longitudinally t'herethrough in the spaced relation in 0 which it is desired to guide the wires to the die |9 In this instance the die'l9 is provided with a pair of die openings 23 and 24 in alignment with the respective wire guiding openings in the tip 2|, and are separated from each other by a bar-like portion 25 of the die member.

In the operation of the apparatus thus far described, the wires or other conductors 0 and I are fed, endwise, by any suitable means not shown, through the guide openings in the tip 2| and into, through and out of the openings 23 and 24 in the die l9. At the same time plastic insulation material is fed to the apparatus by any suitable means, such as a feed screw or worm I6, commonly employed in extruding apparatus.

This worm moves the plastic insulation material to the portions of the wires ll between the forward end of the wire guide 2| and the inlet end of the die IS, and then through the die openings along with the wires being fed through said openings. Thus the insulation material will be applied around the wires in that part of the extruding head which lies between the exit end of the guiding tip 2| and the inlet end of the openings 23 and 24 in the die 19, whereby the wires which are in spaced substantially parallel relation, are embedded in a single body of insulating material in the space between the guide member 2! and the die 19. Thereafter the insulating material will be extruded through the openings 23 and 24 in the die, along with the wires which pass with said material through the openings in the die. The part 25, which lies between and separates the die openings 23 and 24 will divide and separate the insulating material along a plane lying longitudinally between the wires into longitudinal lengths or jackets surrounding the respective wires, and thus the wires with their insulation jackets will issue or discharge separately and independently from the openings 23 and 24 in the die. It will here be explained that the conductor wires l0 and Il are first embedded in a single mass of insulating material 2! in the space between the exit end of the guide 2% and the inlet end of the die l9, and thereafter the part of the die which separates the openings 23 and 24 operates to sever and divide the body of insulating material in which the wires have been embedded, so that the wires embedded in their respective jackets, discharge separately and independently in spaced relation from the die, and are subsequently brought together, (in a manner as will be hereinafter described), with the adjacent faces of the insulat ing jackets in mutual contact while they are still plastic, soft or tacky, whereby an adhesive joint will result between the jackets, the adhesive strength of such joint being less or weaker than the cohesive strength of the material of the jackets, thus permitting of the jackets being readily separated along the joint therebetween merely by pulling the jacket apart by hand. This joint being weaker than the cohesive strength of the insulation material insures a clean-cut cleavage or separation along the plane of the joint between the jackets, and obviates the possibility of tearing portions of the insulation jackets away from the wires and leaving portions of the wires bare and unprotected. The separate insulated wires or conductors will be held together by the relatively weak adhesive joint M for the purposes of transportation, storage, and use, but at the same time may be forcibly separated or torn apart along the joint M.

It will now be understood that there is a simultaneous and continuous feeding of the wires and extrusion of the insulation material through the die openings and consequently a continuous application of the insulation material to the traveling wires in the form of a jacket surrounding each wire.

Any common or preferred means may be employed for feeding the wires endwise, no such mechanism being shown in the accompanying drawing, as it forms no part of the present invention of uniting the insulation jackets of a plurality of insulated wires by a joint having a tear resistance less than that of the insulation material itself, so that mutual separation of the jackets may be accomplished simply and readily by hand and on the job. As shown in Fig. 3, the bar-like separator 25 is of greater width intermediate its ends than it is at its ends, so that the adjacent sides of the die openings 23 and 24 produce longitudinally extending grooves in the side portions of the insulation jackets formed on the wires as the plastic insulation material is extruded through the respective die openings. ment is such that the conductor wires l0 and H are guided approximately centrally through the two die openings 23 and 24, so that the insulation jackets l2 and l3 formed around the respective wires provide a substantial and adequate thickness of insulation entirely around the conductor wires. Preferably the die openings 23 and 24 taper gradually from their inner to their outer or outlet ends, as clearly shown in Fig. 1.

The insulation material covered wires l0 and II issue steadily and continuously from the extruding head and are received between upper and lower guide rollers 26 and 27. The upper roller 2'6 is supported by the free end of an arm 28 which is suitably mounted on a convenient frame part or bracket designated 29. The lower roller 21 is carried by the outer end of an arm which is also mounted on a conveniently located frame part or part of the bracket 29 as indicated. The arm 30 may conveniently be rigidly mounted on the frame part 29, but the arm 28 is preferably pivotally mounted so that the arm 23 with its upper roller 28 may be swung away from the lower roller 21 to facilitate initial threading of the conductors through uniting rolls which will presently be described. The uniting rollers just referred to are designated 3| and 32, respectively, the same being journaled on the free ends of arms 33 and 3d, which are pivoted as indicated at 35 and 36 respectively, on portions of the bracket 29. The rollers 3| and 32 are grooved as indicated in Fig. 2, and adapted to receive between them the two conductor portions l2 and I3. able spring device serves to yieldingly urge said rollers 3| and 32 toward each other so that the two conductor portions I2 and l3 are thereby pressed into contact with each other. When the two conductor portions are thus brought into contact with each other they become united as an incident to the adhesiveness of the plastic material from which the conductor jackets are formed. In the case of plastic, uncured rubber composition which is commonly used for this purpose, the tendency for the two conductors to adhere to each other is adequate to maintain them in this condition while they are fed through a powdering trough and thence through a curing 'or vulcanizing device, or to a tray which, when filled, may be placed in a vulcanizing device.

The spring arrangement for urging the rollers 31 and 32 toward each other is preferably adjustable and in this instance it includes a spring element 31 which is anchored at one end to the pivoted arm 33. At its other end, the spring is anchored to the inner end of a screw 38 which is adjustably carried by the arm 34. A locking wing nut 39 is provided on the screw for locking the latter in adjusted position. By varying the tension on the spring 31, the pressure exerted by the rollers 31 and 32 on the conductor portions may, of course, be adjusted to secure the best results. It will be noted that the depth of the grooves in the rollers 3i and 32 is such It will be noted that the arrange- 1 respectively,

An adjustthat when the two conductor portions are received between the grooved portions of the rollers, the latter cannot contact with each other so that spring pressure is at all times exerted upon the conductor portions as they pass between the rollers 31 and 32.

The bracket 29 is preferably vertically adjustably mounted on a bracket carried by the extruding head or other suitable support so that the bite between the upper and lower rollers 26 and 21 may be adjusted to proper level for receiving the conductors without necessitating bending or flexing of the latter.

It will be noted that in the production of duplex conductors embodying the central opening l (Fig. 4) air is permitted to fill in such aperture during the production of the conductor by reason of the space between the conductor portions intermediate the outlet end of the die I 9 and the point where the conductor portions come together as an incident to the pressure exerted by the rollers 3| and 32.

The die openings 23 and 24 are preferably so shaped that the insulating material jackets formed thereby are free from sharp corners. As an incident to the die opening shape indicated in Fig. 4, the duplex conductor thereby formed is provided with minor grooves designated 40 and 4| on its opposite sides, said grooves communicating with the respective joints I 4 and [4".

After the wire produced by the method explained is suitably treated or vulcanized to render the insulation material resilient or cured, the conductor portions are effectively bonded together so that they will not normally become separated. However, when, for various wiring purposes or the like, it is desired to separate the two conductors while retaining thereon adequate insulation coverings, it is possible to separate the conductors by merely tearing the same apart. The application of suificient force will effect such separation at any point in the length of the conductor or at an end, but in some instances it is more practical to start such separation by shearing or otherwise cutting the two portions apartin the plane of the joint l4 and opening I5. When separation is started in this manner, it is comparatively easy to continue the separation by tearing. The joint and opening serve to guide the tearing so that the rubber jackets of the wires are not themselves torn or otherwise impaired.

If desired, a duplex conductor may be made by the method above described without forming the opening IS in the conductor. In such a case, the joint would extend across the entire thickness of the insulation jacket as indicated in Fig. 9. The width of such joint might, of course, be reduced to accordingly weaken the bond between the two conductor portions by shaping the respective portions in various ways such as typified by Figs. 7 and 8.

In Fig. there is illustrated a conductor construction in which the opening is so shaped that the convex inner side portions of the respective conductor jackets l2 and I 3 approach each other substantially in the plane of the conductors. It is preferable, although not necessary, .n this construction that the convex inner wall )ortions do not contact each other, although if iesired they may be permitted to do so, so as ;0 form a plurality of openings separated by a oint portion substantially as illustrated in Fig. 1. It will be apparent that many opening arangements and cross sectional shapes may be provided While employing the principles of the invention as above explained.

In the arrangement illustrated in Fig. 5 the die element is designated 42, the same being provided with a pair of die openings 43 and 44 separated by a bar portion 45 of the die. In this case, the bar element 45 is of less width than the depth of the die element, so that the jacketed wires issue in spaced relation at the front edge of the bar element. Beyond said front edge, the wires may be guided into engagement with each other by appropriately shaping the front or outlet opening of the die element substantially as illustrated. Suitable provision may be made for permitting air to enter the space in front of the bar 45 and between the conductor wires, for example, vent openings such as indicated at 46 in Fig. 6 may be provided,

It will be apparent that the described plural conductor structure may-be made at very low cost by the extrusion method explained and that more than two conductors may be joined in the manner explained. By the invention described, separation of the individual conductors, retaining thereon predetermined, adequate covers of insulation material may be easily accomplished, mainly by tearing, the line of severance or separation being definitely controlled. Also, the provision of a central opening serves to save material and reduce weight with attendant advantages.

Changes may be made in the described arrangement without departing from the spirit of the invention, the scope of which should be determined by reference to the following claims, the same being construed as broadly as possible consistent with the state of the art.

I claim:

1. The method of making divisible duplex insulation covered electric conductors which consists in feeding spaced conductor Wires endwise,

extruding insulating compound in plactic condi tion around the moving wires, and, as an incident to the extruding operation, dividing the insulation in a plane intermediate the wires into separate complementary parts, bringing the complementary insulation parts into contact with each other and thereby uniting them by a joint which has a tear resistance less than that of the insulation material.

2. The method of making an electric conductor cable, which includes: the steps of feeding spaced conductors endwise, embedding the moving conductors in a moving body of plastic material, dividing the moving material longitudinally between the embedded conductors into separate parts each including an embedded conductor, and then bringing the moving parts into mutual contact while the material is still plastic to thereby adhesively unite said parts.

3. The method of tor cable, which includes the steps of feeding spaced conductors endwise, embedding the condoctors in a moving body of plastic material, directing the moving material and the wires embedded therein to ings with the wires passing through respective openings and thereby dividing the embedding material into separate parts each containing an embedded wire, and then bringing the moving parts into mutual contact while in a plastic condition to thereby adhesively reunite the parts.

4. The method of making an electrical conductor cable, which includes the steps of feeding spaced conductors endwise, embedding the conmaking an electrical conducand through separate die open ductors in a moving body of plastic material, directing the moving material and the wires embedded therein to and through separate die openings with the wires passing through respective openings and thereby dividing the embedding material into separate parts each containing an embedded wire, and then bringing the moving parts into mutual contact while in a plastic condition and within the die to thereby adhesively reunite the parts.

5. The method of making an electrical conductor cable which includes the steps or" feeding spaced conductors endwise, embedding the conductors in a moving body of plastic material, directing the moving material the wires em bedded therein to and through se arate die openings with the wires passing thri 'lgh respective openings and thereby dividing the embedding ma terial into separate parts each containing an embedded wire, and then bringing the moving parts into mutual contact while in a plastic condition and outside of the die to thereby adhesively reunite the parts.

6. In the making of duplex insulation covered electrical conductor cord wich may be torn apart into individual conductors each retaining predetermined portion of the insulation of the duplex conductor, the steps of feeding spaced wires endwise through a die. simultaneously eidruding a longitudinally flattened jacket oi plastic material through said die and around each wire, and then guiding such insulation covered wires toward each other and bringing the flattened suriaces *hereof into contact with each other exter r and while in a plastic condition to thereby adhesively unite the parts.

7. In an extrusion apparatus for making separable, plural-wire conductor cord of the class described, the combination of an extrusion head provided with a die having a plurality of relatively independent openings therein, means for guiding conductor wires through the die openings, means for moving and directing plastic insulation material through the die openings and round the wires as jackets thereon as they pass through the die openings, and means for guiding the jacketed wires toward each other and bringing surface portions of said jackets into mutual contact while in a plastic condition to adhcsively unite the same.

8. In an extrusion apparatus for making separable, plural-wire conductor cord of the class described, the combination of an external head provided with a die having a plurality of relatively independent openings therein, means for guiding conductor wires through the die openings, means for moving and directing plastic insulation material through the die openings and around the wires jackets thereon as they pass through the die openings, and means comprising a portion of said die i r guiding the coated wires toward each other and for bringing surface portions of said jackets into mutual contact while in a plastic condition to adhesively unite the same.

9. In an extrusion apparatus for making separable, plural-wire conductor cord of the class described, the combination of an external head provided with a die having a plurality of relatively independent openings therein, means for guiding conductor wires through the die openings, means for moving and directing plastic insulation material through the die openings and around the wires jackets thereon as they pass through the the openings, means independent of said die and spaced outwardly therefrom for guiding the jacketed wires toward each other and bringing surface port-ions of said jackets into mutual contact while in a plastic condition to adhesively unite the same.

10. The method of making divisible duplex insulation covered, electric conductors which consists in feeding spaced conductor wires endwise, extruding insulation compound in plastic condition around the moving wires, forming a cleft in the insulation compound in a plane intermediate the wires, and closing the cleft by bringing together the walls thereof, while the insulation compound is in plastic condition, thereby to adhesively unite said walls.

11. The method oi making an electric conductor cable, comprising the steps of feeding spaced conductors endwise, embedding the moving conductors in a moving body of plastic insulation material, par g the moving material longitudinally between the embedded conductors, and then re-joining the moving parted portions while the material is stiil plastic so as to thereby adhesively unite said parted portions.

1.2. In an extrusion apparatus for making separable, plural wire conductor cord of the class described, the combination of an extrusion head provided with a die having wire passes therein, means for guiding conductor wires through said passes in spaced relation to the die walls forming said passes, means for applying plastic insulation material to said wires as they are guided through said to thereby jacket said wires with said insulation material, said die having a rib between passes and said rib serving to form a cleft in said jacket in a plane intermediate the wires, and means for engaging and guiding the cloven jacket so as to close the cleft therein while the jacket material is in plastic condition, thereby to adhesively unite the walls of the cleft.

13. In an extrusion apparatus for making separable, plural wire conducto-r cord of the class (if ed, the combination of an extrusion head provided with a die having wire passes therein, means for uiding conductor wires through said passes in spaced relation to the die walls forming said passes, means for applying plastic insulation material to said wires as they are guided through said passes to thereby jacket said wires with said insulation material, said die having a rib for parting the insulation material extruded through said passes in a plane between said wire, and means for guiding the parted insulation material together again while the material is in plastic condition, thereby to adhesively unite the parted material.

HUGO H. 'WERMINE. 

